Due to the rapid development in information communication technologies, the amount of information or a transmission capacity of a network has greatly increased. High speed and large capacity transmission on the network is realized using optical fibers, however, optical signals are converted into electric signals at nodes of the network for processing information.
Since optical signals are converted into electric signals, the communication speed on the network is limited. Therefore, optical information processing technology, which may process the information without converting the optical signals to the electric signals, is advantageous.
An optical memory device, e.g., a memory which may record/reproduce information by using light, is important in the field of optical information processing technology. Various types of optical memory devices have been suggested, however, an optical memory device having a structure having recording/reproducing properties and which may substitute conventional memories has not been suggested.